Many different types of devices are able to generate a theatrical vapor. For example, one type of vapor generator is a smoke machine. Most smoke machines typically vaporize a water and glycol-based fluid mixture to emit a dense vapor that resembles smoke or fog. In operation, the smoke machine injects the fluid into a heated block or chamber where it quickly evaporates into a vapor. The resultant pressure forces the vapor out of the chamber and into the cooler ambient air, where it forms a fog or smoke.
There are many different uses for such devices. For example, the entertainment industry uses smoke machines to create spooky theatrical effects, or to enhance lighting effects. Smoke machines are also useful for industrial purposes, such as visualizing the flow of air in a wind tunnel. Additionally, smoke machines are frequently used in commercial Halloween displays, and have become widely used for domestic Halloween decorations in residential areas.